MOSCOW (AP) — A Frenchman who amassed an arsenal of weapons, explosives and tactical gear was plotting to attack the European Championship soccer tournament and was arrested trying to cross into the European Union from Ukraine, officials said Monday.

Ukrainian agents had been following the man since December, and allowed him to buy five machine guns, two rocket-propelled grenade launchers, 125 kilograms (275 pounds) of TNT, 100 detonators and other arms. He also bought 20 balaclavas before he was arrested at the Yahodyn border crossing between Ukraine and Poland last month, the Ukrainian Security Service said.

The intelligence agency, known as the SBU, "has managed to foil a series of 15 terrorist attacks which were planned to target France before and during" Euro 2016, said its chief, Vasyl Hrytsak.

Ukraine didn’t identify the man but said the suspect wanted to protest his government’s migration policies and the spread of Islam. It said he planned attacks on bridges, railways and other infrastructure for the Euro 2016.

The Paris prosecutor’s office, which handles terrorism cases at a national level, said no investigation had been opened yet. France’s foreign ministry confirmed the arrest in Ukraine, but offered no details.

Extremist attacks are a major concern for French authorities as they prepare to host the monthlong tournament at stadiums in the Paris area and eight other cities from Friday through July 10. Islamic State extremists have threatened France during the tournament, but authorities haven’t confirmed specific dangers.

France is deploying a 90,000-strong security force for the tournament, and President Francois Hollande said Sunday night that the threat of attacks won’t stop it from being successful.

The Paris police prefect, Michel Cadot, declined to comment Monday on the information from Ukraine, saying only that "there is no specific threat against any (Euro 2016) site."

Ukraine’s intelligence agency went public about the arrest after reports in international media, Hrytsak told national television.

French regional newspaper L’Est Republicain identified the man as Gregoire Moutaux and said investigators raided his home in Nant-le-Petit near the eastern city of Nancy in late May. The source for the man’s identity wasn’t cited. French television network M6 reported that investigators found T-shirts promoting an extreme right group.

Ukrainian authorities released photos of a fair-haired man, with his face blurred, holding various weapons, as well as a video of the arrest which showed special forces officers dragging the man out of a white minivan and putting him face down on the ground of what looked like a parking lot.

The Frenchman arrived in eastern Ukraine last year and was "trying to establish ties with Ukrainian troops under the guise of volunteering," the Ukrainian agency said.

Ukrainian troops and Russia-backed separatists have fought in the east since April 2014, killing nearly 9,400 people. It wasn’t immediately clear which side of the conflict the Frenchman had stayed with.

"The Frenchman spoke negatively about his government’s migration policies, the spread of Islam and globalization," the SBU said. "He also said that he wanted to perpetrate acts of terror in protest."

Cadot, the police prefect, said security measures tested since the Nov. 13 attacks in Paris that killed 130 victims have been adapted to fit Euro 2016. In those attacks, three suicide bombers detonated their explosives at the national stadium, while two other squads of attackers unleashed gunfire in central Paris.

Cadot promised "a close security perimeter and an outer security cordon that will create a bubble even before the checkpoints." He said visual controls, bag and ticket checks and some pat-downs aim to stop someone from carrying in explosives.

Stadiums used in the European Championship soccer tournament in France:

___

Lori Hinnant and Samuel Petrequin in Paris contributed to this report.